G60 Polyglas GT=s - wheel balance weight issues

Discussion in 'The Hides' started by buick64203, Nov 21, 2018.

  1. buick64203

    buick64203 Just plum crazy Staff Member

    What is an acceptable amount of weight for a new G60-15 Polyglas? Seems that in general these tires just take a lot of weight. For example I had a new set mounted and 2 of the tires took a little over 4oz of weight. We used a Hunter road force balancer and the wheels were pin straight according to the unit. All the imbalance is in the tire. Even using the "smart weight" option didn't correct it. Smart weight is just Hunter jargon for match mounting- orienting the wheel and tire so that it uses the least amount of weight. The two others balanced out just fine using a normal amount (1 to 2 oz per wheel)

    What say you? Is it normal for these tires? Did I get 2 bad tires? Should I complain? Live with it? How did yours balance?
  2. Dano

    Dano Platinum Level Contributor

    There's actually much more to the smart weight than that and unfortunately, most people who have that machine don't really understand it or use it to it's fullest extent. I can't get into a dissertation here (call me if you need help or want me to do these for you - Worth the trip & I'll make them ride smooth as glass) but basically, there's two things that cause wheel/tire vibrations:

    1) Out of round (or as Hunter calls it, Force Variation which can be either out of round or hard regions built into the construction of the tire but both present the same)
    2) Out of balance.

    The two are only marginally related and if the assembly (important as every wheel and tire is out of round and the "match mounting" of the high/low in each is where that machine is earns it's money) is out of round it will shake no matter how well it's balanced (think, you can balance a crank, but would it roll smoothly?) and likewise, if round but not balanced it'll also shake - Both typically occur @ different speeds and more than one "bad" assembly changes things. Once an assembly is round (an out of round tire and an equally out of round wheel are a "match" made in heaven in the right hands and a vibrations disaster in the wrong ones), I really don't worry too much about the weight unless it's extreme and 4 oz. wouldn't faze me. Also, are we talking about static or dynamic balance and if dynamic, are they hiding the weights behind the center disk, which invariably causes the weight to go up because the planes are so close. This is all assuming they didn't put a cone through the center and are properly centering the wheel on the machine off the stud holes, just as it's centered on the car with the tapered seat lug nuts. If not, then any results you're seeing are more or less worthless. On a passenger car, I'm looking for around 15 lb. of 1st harmonic "Road Force" (or 2nd or 3rd harmonic, but usually only see that in truck tires). There's still more to it without giving away the secret sauce, but that's the basics.
  3. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    Put them on the back and go racing. It's a big tire really. 4 oz really isn't much.
  4. gsx455-4ever

    gsx455-4ever Gold Level Contributor

    4 OZ isn't really too much . If you said 7 or 8 I would say get 2 new tires . There is a formula for calculating how much is too much . I don't remember exactly but its something like 1% of the total tire weight . Once you cross that mark its too much .

    I recently bought a set of BF Goodrich all terrain tires . 265/75 R 17 . When I got home I glanced at the RR tire . It had 8 OZ of weight on the outside of the tire . I crawled under the Suburban and looked at the inside of the tire . It had 9 Oz on the inside . That's a total of 17 OZ on one tire . Over a pound . I called them up , a local chain tire store and they said , " well that's where the tire balanced out at " . I went to my friend at the dealer and he tried to balance it , even moving it around on the rim and it still needed 17 OZ . He broke the tire down and checked the rim . It was perfect . I drove back to the tire store and they said my rim was that far out of balance . I told them if my rim was that far out it would have to be missing a chunk of it at least 4 inches square and would never hold air .

    They told me they would check it and see. After a long battle they finally got me another tire . But I bet the next customer that needed a tire that size they got the one they took off of my Suburban

    So if a tire actually weighs 30 pounds the maximum allowed weight should be 4.8 OZ
    Last edited: Nov 21, 2018
  5. buick64203

    buick64203 Just plum crazy Staff Member

    Interesting stuff Dan, thanks for posting. Since these were factory GM wheels, I thought Id be good to go balancing them through the center hole. My understanding was that factory GM wheels were hub centric. I did balance my Wheel Vintiques thru the lugs as WV said their wheels were lug centric.

    These are original GM black steelies. And they were perfect. We balanced them dynamically- weights on both sides with old school clip on's- the best balance IMO. After adding the 4oz's they came up zero on the next spin. These two did come up with a .0031" and .0032 run out.
  6. 1970 STAGE 1

    1970 STAGE 1 Well-Known Member

    By dual plane balancing like you did , 4 ozs. is not bad for belted tires. As stated also , out of round can not be corrected or compensated for by balancing. I am a retired Firestone employee and have mounted and balanced a few tires..
  7. Dano

    Dano Platinum Level Contributor

    By definition, if a wheel uses tapered or radius seat lug nuts, it's lug centric and if flange nuts, it's hub centered although the OEM's, especially on newer vehicles do make the hub bore fit pretty snugly to the hub even on lug centric wheels. I believe this is to pre-center the wheel as they have a 4,5,6, or 8 spindle gun that tightens the nuts all at once on the assy. line and even in service work, if the wheel isn't pre-centered and one tightens the 1st nut and "pulls" the wheel up with the nut, it will potentially flex the stud slightly. Many times, aftermarket wheels are made with a larger hub bore for a more universal application or for use of a "push-through" hub cover (we do) and in that case, I'll put a prybar or piece of wood under the tire and lift up on it to take the pressure off and snug the first couple nuts. That's also where the use of hub rings comes into play but honestly, on a lug centric wheel, despite many in the industry that disagree with me, I don't think they're actually necessary except, as I said, to pre-center the wheel.

    The problem with a cone is that it's a stamped wheel center and there's no need for that surface where the cone is seating to be uniformly formed so the cone may or may not be centering the wheel although the machine you were using does have a "centering check" feature which I'd bet on 99% of them has never been used more than twice - Once during the initial training and once when a tire tech got curious.

    Was the .0031/2" (not 0.031"?) Runout lateral (side to side) or radial (up/down or out of round) and in the wheel or wheel/tire assy.? Not saying you're incorrect here, but as one of my professors used to say when we'd complain about getting marked down for a decimal point in the wrong place "That's the difference between the bridge falling down or not." .003x is darn good either way - Almost too good. If .03x, lateral is marginal and would be taken care of by a dynamic balance but if radial you'd feel that. Typically, you "see" lateral but "feel" radial runout in wheels/tire assy's and for some reason, people often assume the problem is in the wheel, which is a solid piece vs. the tire which is a deformable composite of several materials often laid up by hand and cooked under pressure in a mold. Tires and wheels both have lateral and radial runout. Nothing is perfect.

    In the end, the proof is in pudding - Does it vibrate? It shouldn't - At all, assuming you have good shocks. The factory goes to great lengths to make sure new cars ride smoooooth on their OE tires - The little green/orange stickers, paint marks, etc. on new car's wheels/tires mean something and are the reason that replacement tires almost never ride as well - "it came up zero-zero" is only half the story, and IMHO, the least important half. I guarantee my old beater cars ride smoother than most new cars on their 1st set of replacement tires.

    What's even crazier and downright evil and honestly I'm not sure if this still goes on but I wouldn't be surprised, is that the OE's, if they have some strange harmonic in the drivetrain, will have a tire specially designed to counteract that so the car rides smoothly when new. Of course the aftermarket version of that "same" tire doesn't have that design "feature" and that vehicle will never ride as smooth as it did from the factory.

    And then there "pull" or conicity, that'll have to be another day.
  8. buick64203

    buick64203 Just plum crazy Staff Member

    Sorry, it was .031!....duh:p Read it wrong. Good thing Im not an engineer!:D

    Anyway, here's the sheet

  9. UNDERDOG350

    UNDERDOG350 350 Buick purestock racer

    For a welded steel wheel and those big of tires 4oz is nothing. These wheels ABSOLUTELY MUST BE MOUNTED TO THE BALANCER USING ONLY THE 5 LUG STUDS. Yes I was shouting because nobody listens. You can not apply 2018 technology to 1950's technology. Is does not relate. Same as attempting to do a 4 wheel alignment on a 1970 GS. The numbers do not relate and the 25 year old Tech freaks out thinking the car was totaled at some point. Do not overthink this.
    dynaflow, kack and gsx455-4ever like this.
  10. Dano

    Dano Platinum Level Contributor

    I would suspect that you have a little bit of a vibration, again knowing that the cone is dubious @ best so who knows what you really have. Assuming it's all at least realtive, which may or may not be the case, getting the two rears rounder may bring the weight down, but not necissarily. Depending on the lateral runout of the assembly I probably would've put the two worst on the front. Good way to tell, as the machine won't measure that, is the farther apart radially that the front and rear weights are, the more lateral runout there is as the dynamic balance is counteracting that, which is why I said you "see" lateral and "feel" radial runout. The reason I'd try them on the front is that the weight of the engine will tend to flatten the tire more as is rolls whereas with less weight (I.e. on the rear) it'll literally try to lift the car and cause a vibration. It's akin to when you put weight in the back of a pickup truck and it smooths out (not the harshness, but the vibrations). In this case, throwing 4-500 lb. in the trunk would have the same effect and as a test, would tell you if they were causing a problem.

    Again however, as did Steve, I cannot stress enough that the results from the cone are dubious.

    As far as the 2 lb. pull, it takes a lot more than that to make it actually drift but given the choice, I'd put them like you have if I drove more on the highway and in the left lane to counteract the crown in the road and the other way if I drove more in the right lane or on two lane roads.
  11. Dano

    Dano Platinum Level Contributor

    You said it more emphatically than I did Steve (I owe you a phone call - Sorry, life has gotten in the way), but of course you are correct. The cost of the fixtures to properly center wheels on balancers can easily exceed the cost of the balancer depending upon how broad of applications one wants to cover.

    I was speaking with a QC engineer @ a major truck wheel manufacturer once and we got onto this subject and I was telling him about one fixture I'd had to special order from Germany and he said he couldn't get the engineers @ Isuzu, who needed this same fixture, to understand this concept.
  12. gstewart

    gstewart Well-Known Member

    Steve is right on the money. Our rims are lug/stud centric and require an adapter that will perform the proper balance. The last time my tires were balanced the adapter was used. No complaints. I believe that I will be replacing the T/A's on my '72 GS and the seller for the new tires has the proper equipment to do a proper balance.
  13. Brad Conley

    Brad Conley Super Moderator Staff Member

    Slight thread drift.....

    I just replaced the tires on my 85 GMC tilt-rollback as the old tires were of drinking age :)eek: - 34th week of 1996 was the date code). The tire dealer I used had the proper adapter to use the lugs and not a cone in the hub. I was amazed at the smooth ride on my way to Chicago for MCACN's.
  14. buick64203

    buick64203 Just plum crazy Staff Member

    Brad- When we changed the tires on the truck a few years ago, we took off a set of old all terrain style tires and bought a set with more of a highway style tread. The old tires must of been octagon shaped! I never realized exactly hoe bad they had gotten till I put the new set on. It felt like I was driving a Cadillac! Tires are like shocks- you don't really notice the degradation until the new set goes on

    What Im going to do is this- Im going to install the new tires on the beater this weekend. The car has to go in for an alignment this week. Not only to protect the new tires but to straighten the wheel. The place Im bringing it to has a brand new Wheeltronics lift, a JBC V3D image aligner and a guy that really knows his stuff. And on top of it, I trust him with my baby. Im going to ask him to check the balance on the two tires that took the 4oz's of weight while its there. So we'll see what he says when I pick it up. I'll ask him if he's got the lug adapter. I have a feeling by the looks of the shop that he does. So stay tuned!

    Dan, you would of loved the Hoffman Prufrotor I had when I worked for snap on. It was a tool for calibrating balancers. It mimicked a perfectly balanced 15x6" wheel. And it had a certified 3oz weight that screwed onto it. So you could not only test to make sure it calculated the correct amount of weight but also check the plane separation
  15. Dano

    Dano Platinum Level Contributor

    On an '85 GMC, that's a hub centric wheel (OE used a clamping plate and tapered seat nuts, which has the same effect as flange nuts) & there is a fixture that fits the hub bore of those wheels to center them just like they center on the axle (a flange, not a cone) and then an 8 stud finger plate that fits around it (I'll have to grab a pic) basically to stabilize the whole thing. Very few shops would have it. By centering it off the lug holes, they're assuming that the bolt circle (PCD - Pitch Circle Diameter) is concentric with the bore, which on that wheel it is to a pretty reasonable extent although the bolt holes are punched vs. machined, and if so, you could actually get a better result.

    That's because the biggest issue with hub centering wheels is that any variation between the hub bore of the wheel and the machined centering surface on the axle introduces radial runout. Trick there is if you know where the high spot is in the wheel/tire assembly, is to position it @ 12 o'clock so it "drops" and it'll effectively make the assembly run truer. Might pick up .002"-.005" on that truck depending on the tolerance stack which is sometimes enough to fix, or at least help fix a problem. Throws the balance off, but there's a fix for that too.

    When I open the hub bore up on a hub centric wheel to fit a different application, I mark the average low spot of the inner/outer beads and then offset the new bore slightly to "fix" the radial runout in the wheel. Then the bore and PCD are no longer concentric, but it doesn't matter since the bore is what's centering it and as long as there's clearance between the lug hole & the stud but it's not a huge amount of offset. In that case however, you're tire shop's method would've been an issue.

    On some trucks (GM 4500/5500 series are notorious for vibrations), the variation between the bore and axle can be so big that they make a sleeve that threads onto 3 of the studs to effectively stud center a hub centric wheel. Then put the other nuts on snug and remove the sleeves. Once you torque all the flange nuts down on a hub centric wheel, the wheel won't move (I.e. The load is carried by the clamping force of the nut - The center bore carries zero load - it's for centering only).

    Was nice to finally meet you last weekend after all these years and to see your cars again. Had been a long time.
  16. Brad Conley

    Brad Conley Super Moderator Staff Member

    I don't know hub from lug centric but the guy, who does a ton of heavy duty trucks, had this device that bolted thru the lug openings and, now that you mention it, a flat disk like thing that went into the hub. I had never seen such a device before but whatever it was, it made a huge difference in the quality of the balance.

    Nice to meet you too Dan! That was quite the event and, while I'm worn out, was well worth the effort!
  17. buick64203

    buick64203 Just plum crazy Staff Member

    So I called Kelsey tire abut this issue. They were adamant that the tires needed to be balanced through the lug nut holes before they would even entertain any talk of an exchange. They also wanted photographic proof of the tire mounted on the balancer with the adapter. So back to the tire shop we go will cell phone in hand. After rebalancing though the lug nuts holes, the final outcome is 7.5oz on one and 5.5oz on the other. Actually came out worse. We couldn't get it any better. Even breaking the tire down and rotating the wheel and tire 180 out, the weight chased the tire. Mind you that the two other tires took minimal weight- less than 2oz each.

    So I called back Cathy, who put me through to a gentleman who wouldn't give me his name. When he asked, he said he "was the guy who owned the place". I could see where this was going. So I explained the whole story to him and he said that he would only replace one tire, the tire that took 7.5oz. But not the other one. Even after I explained that I have purchased 15 G-60 tires from them for 3 cars (12 tires + 3 spares) and NONE of them took anywhere close to this amount of weight. Didn't matter. I explained that the 4.5 of the 5.5oz was on the front and I run doggies. I also explained that Ive purchased numerous sets through my account for customers (aka friends). Didn't matter. Guy wasn't budging. That in NY is called "not doing the right thing" by a customer. His suggestion on the other tire with 4.5 oz on the front was to "just take an ounce of weight off cause you wont feel it anyway". I wound up having to take his gracious offer of the exchange on the one tire. My luck the replacement will be worse.

    I told him his customer service sucks and I wont buy another tire from his company ever again. Eff him. I'm half thinking about just disputing the charge on my CC now.
    TexasT likes this.
  18. pbr400

    pbr400 68GS400

    I’m guessing most of his customers don’t feel any problems (you know, when they’re pushing or driving at 3 mph from the trailer to the show field).
    You people who drive on repro tires, y’all just troublemakers!
    mrolds69 likes this.
  19. buick64203

    buick64203 Just plum crazy Staff Member

    And to add insult to injury, the invoice they emailed me says, "we appreciate your business". Actually, you don't. If you did, you'd be warrantying 2 tires
  20. TexasT

    TexasT Texas, where are you from

    I wouldn't dispute it but I would tell every one you know about the shady service and lack of customer awareness of the place. I'll probably never be buying tire like that so me stating I'd not do business with em won't do any good but i will NEVER buy another KYB shock due to the same type of problem. and f kyb!
    Last edited: Dec 8, 2018

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